


Promise Me?

by TheFluidGender



Category: Undertale (Video Game), Voltron: Legendary Defender
Genre: Crack, I Can't Believe I Wrote This, M/M, Minor OC - Freeform, but she is basically just there for the prologue and in mention, like really bad, she isnt important rip, umm, yepperooni
Language: English
Status: In-Progress
Published: 2018-08-19
Updated: 2018-08-19
Packaged: 2019-06-29 23:49:46
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 1,159
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15739809
Author URL: https://archiveofourown.org/users/TheFluidGender/pseuds/TheFluidGender
Summary: Long ago, monsters and humans waged war against each other. Monsters and people alike were killed, others separated. Two monsters, binding their families together into one, are f those separated. One underground, the other to space. One shall see the end of war on Earth, the other thrown into a new war. A war for the universe.....Now that the pleasantries are out of the way, what happens when they grow up, and he who was sent to space comes back?





	1. Prologue

**Notes for the Chapter:**

> EDIT 1/26/19: Don't mind me I just re-edited the first chapter and am working on everything again. This isn't abandoned I swear I just need to rework it.
> 
> Catch you on the flip side, my dudes.

Two small monsters sit under a tree. One a skeleton, the other a creature with eight arms, a beak, and a body that can twist and contort much like his prehensile tail.

“Sans?” Asked the beaked creature.

The skeleton turns. “Yeah Slav?”

“When we grow up, let’s go on a date!”

Sans smiles. “Yeah! When we grow up, we’ll be the cutest couple in the world!”

“Promise in this and all realities?”

“Promise in all realities.” A bony pinky links with one of many flesh ones, and the deal is sealed.

* * *

Everything is burning. The humans have come to destroy them.

“Slav!” Sans is screaming for his friend, running alongside his father, W.D. Gaster, who is clutching his baby brother Papyrus.

“Slav!” He screams again.

“Sans!” A voice echoes, and he can see Slav and his mother standing by a weird contraption. It’s the thing their parents have been working on since war was first declared.

“Hurry!” Slav is held in his mother’s many arms, and they’re inside the main chamber of the machine, the door flung wide open. His glasses are slipping off his face. The humans are closing in on the machine, and Gaster knows his family won’t make it in time.

“Sonja, go! We won’t make it!”

“What about you and the boys?!” she questions, furtively glancing between the skeletons and the humans.

“We’ll figure something out, now go!”

The pair tearfully gather their children, both screaming no, this can’t be happening they can’t leave each other. The glasses fall to the ground, and the door slams shut. Gaster runs the other way, away from the humans. The machine rumbles before shooting into the sky. Slav is gone. 

When they return later, all that is left are a pair of glasses. Slav’s glasses.

They’ve lost the war, and while the three are alive, they’re forced underground with the rest of the monsters.


	2. Chapter 2

With a sigh, Sans plops himself down on the windowsill. It's been a while since the kid has freed the monsters, long enough for them to have their rights and even decrease the segregation between the two species. Yet Sans can't help but feel that something is wrong... Something is missing.

His pinprick gaze drifts across the room and lands on his telescope that he brought from the Underground. There wasn't a real reason to have it, as he couldn't see the stars underground. The closest was the bioluminescent buds that grew among the algae high above on the roofs of the caverns. Yet every night we would pull out his telescope, and stare at them for hours. Sitting there pretending that they were real stars. That he was still out there.

His moods sombers. That's right. Today marks twenty years since they were first forced underground. Thirty years since Slav was taken from him. Twenty years since he first acquired the glasses he holds in his left pocket. Hand always encompassing them and never letting go (except to occasionally wear them on really bad days, when thoughts from every timeline plague him and he misses Slav so much because  _ he would love the proof of the alternate realities _ ). He takes them out of his pocket, his left one, and examines them. Though old and slightly worn from carrying them all these years, he's sure to never leave a scratch on the lenses or to allow them to become dirty. He's afraid that if they break or he lets go, then he lets go of Slav.

He clutches it closer for one more heartbreaking moment, then places it back in the safety of his pocket. He knows it's foolish, but he keeps hoping that Slav is still alive. If humans can survive space, with their fragile bodies and SOULs, why can't a monster?

He ponders this for a long moment, when movement from outside the window catches his eye. There's something descending from the clouds. Is that... a ship?

It descends from the clouds, and immediately there is a broadcast He stares at the creature, covered in lavender fur, and with one synthetic eye. He doesn't register anything beyond the fact that he is the one on the ship. That he's an alien. That the universe can truly support life. That Slav may still be alive.

That's when the attack starts.

  
  


_ Thank goodness for the Underground. _

He never thought that he would think those words, yet here he is. When the aliens, now confirmed as the Galra that Samuel Holt spoke about before the monsters breached the surface, attacked, it was instant chaos. Buildings were rapidly being destroyed and everything was burning just like all those years ago. Sans didn't delve into the trauma that surely formed, instead he raced to find his friends and family and make sure they're safe. Papyrus, Toriel, Undyne, Alphys, Grillby, Asgore, _ Frisk _ . So many people to find, to keep safe. He can't lose anyone else.

Thankfully, they all had the same idea, and they find each other and head to Mount Eskel. Humans and monsters alike raced towards the entrance, to reach the place where the Galra could not.

Everyone in their little group was accounted for, including most of Frisk's family (one of their aunts works at the Garrison, so there wasn't any time to grab her). Everyone was mostly okay with some scrapes and bruises and  _ of course _ Undyne sprained her arm trying to protect as many people and monsters alike, and getting hit with building debris. With everyone accounted for, they began to wait out the Galra. Everyone crossed their fingers (or claws or tentacles or whatever appendages they had) and hoped that the Galra would not reach them. They sent out scouts to make sure that every entrance or exit was sealed, and the underground tunnels around made by humans for their hover trains were empty. Sans was one of these scouts. He was sent to the tunnels, and he heard movement echoing from one of the platforms. He quietly began to approach, and then blaster fire could be heard. There are humans fighting against a Galra patrol and from the looks of it, the sentries are pushing them back. He moves closer, eyes widening as more sentries begin to converge on a woman as four young adults ( _ teenagers _ he thinks to himself in horror) flee into a hover train. His eyes widen as he recognizes said woman, being Veronica, Frisks’ aunt. The train begins to pull away, and his horror mounts as she yells for the teens to leave without her.

He wastes no time launching himself towards her, recognizing the tell-tale signs of blaster overload, even within the mounted station she’s using, and reaches out to wrap magic around her SOUL in order to protect her life. She gasps, her head whipping towards him before the blaster explodes. He uses his levitation to yank her towards him, and takes her into his arms and runs as the entire chamber begins collapsing.

**Notes for the Chapter:**

> Sorry for the short chapter and really long wait lol. I'm working on this slowly, I promise. It's been a little difficult for me lately because I'm in two clubs, just finished a play, and doing track all at the same time. Slowly but surely I'll be working on this, and getting all my plot notes down. Comments and ideas of where to take this would be appreciated??? Maybe I'll take this down and repost it all as a one shot for Slans bc that's what this is all about lol. See y'all soon!

**Author's Note:**

> Hi yes this is a crack ship but I've grown strangely invested in it? Ever since a friend of mine introduced me to it?? Cross posted from tumblr where I co admin with said friend (Nerdiest Fan Nerd) though it's more of a side thing nowadays. But I am still the author regardless! Also I haven't actually posted an official fan fiction in like three and a half years, so my skills are a little rusty shhh. And Ao3 is weird and fancy I feel old... (was a fanfiction.net kiddo). Anyways, I'd love to know what you think haha!


End file.
